1. Field of the Invention
This invention relates to a passive device and a method for fabricating the same, more particularly to a chip resistor device and a method for fabricating the same.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional chip resistor device 1 which has a plurality of passive components for providing a range of resistance. The conventional chip resistor device 1 includes: four resistor units, and an insulating ceramic substrate 11.
The insulating ceramic substrate 11 is a thin plate with a rectangular shape, and has a first surface 111, a second surface 112 opposite to the first surface 111, a pair of opposite short lateral surfaces 113 each of which interconnects short edges of the first and second surfaces 111, 112, and a pair of opposite long lateral surfaces 114 each of which interconnects long edges of the first and second surfaces 111, 112.
Each of the resistor units includes two generally C-shaped and spaced-apart electrodes 12 and a resistor 14. The electrodes 12 of each of the resistor units are respectively formed on the two opposite long lateral surfaces 114, and are spaced apart from the electrodes 12 of the adjacent one of the resistor units. Each of the electrodes 12 of the resistor units has two ends that respectively extend onto the first and second surfaces 111, 112. The resistor 14 of each of the resistor units is formed on the first surface 111, and is disposed between and electrically contacts the corresponding electrodes 12.
In use, the end of each of the electrodes 12 that extends onto the first surface 111 is soldered and electrically contacts a circuit board (not shown) so that the resistor units can provide desired resistances to the circuit board by virtue of the resistor 14 between the two corresponding electrodes 12. That is, the electrical path for each of the resistor units is formed by the ends of the electrodes 12 formed on the first surface 111 and the resistor 14. The parts of the electrodes 12 of each of the resistor units that are formed on the long lateral surfaces 114 and the second surface 112 do not constitute the electrical path but provide adhesion strength between the electrodes 12 and the insulating ceramic substrate 11. However, such electrode design would increase manufacturing costs and results in high temperature coefficient of resistance (TCR). Moreover, in test or in use, collision of the parts of the electrodes 12 formed on the long lateral surfaces 114 and the second surface 112 would also result in malfunction of the chip resistor device 1.
Besides, when the conventional chip resistor device 1 is further miniaturized, a short-circuit problem may occur due to an excessively narrow distance between adjacent ones of the resistor units.
Also, upon manufacturing the conventional chip resistor device 1, pin-holes are formed, which might result in sintering deformation and reduced usable area of the insulating ceramic substrate 11. Take a chip resistor device with 0201×2 size as an example, the proportion of the usable area is merely 15%.